Trackball for a computer



FIG. 1 is a top, front, right side perspective view of a trackball for acomputer showing my new design;

FIG. 2 is a top plan view thereof on a greatly enlarged scale;

FIG. 3 is a right side elevational view thereof, the left sideelevational view being a mirror image;

FIG. 4 is a bottom plan view thereof;

FIG. 5 is a front elevational view thereof;

FIG. 6 is a rear elevational view thereof.

The ornamental design for a trackball for a computer, as shown anddescribed.